Reverse Shoulder Arthroplasty (RSA) is recognized to be an effective solution for rotator cuff deficient arthritic shoulders, but there are still concerns about impingement and range of motion (ROM). Several RSA biomechanical studies have shown that humeral lateralization can increase ROM in planar motions (e.g. abduction). However, there is still a debate whether humeral lateralization should be achieved with a larger sphere diameter or by lateralizing the center of rotation (COR). The latter has shown to decrease the deltoid moment arm and increase shear forces, where the former may pose challenges in implanting the device in small patients. The aim of this study was to evaluate how humeral lateralization achieved by varying COR lateral offset and glenosphere diameter in a reverse implant can affect impingement during activities of daily living (ADLs). Nine shoulder CT scans were obtained from healthy subjects. A reverse SMR implant (LimaCorporate, IT) was virtually implanted on the glenoid and humerus (neck-shaft angle 150°) as per surgical technique using Mimics software (Materialise NV). Implant positioning was assessed and approved by a senior surgeon. The 3D models were imported into a validated shoulder computational model (Newcastle Shoulder Model) to study the effects of humeral lateralization. The main design parameters considered were glenosphere diameter (concentric Ø36mm, Ø40mm, Ø44mm) and COR offset (standard, +2mm, +5mm), for a total of 9 combinations for each subject; −10°, 0° and 10° humeral components versions were analyzed. The model calculated the percentage of impingement (intra-articular, contact of cup with scapula neck and glenoid border; extra-articular, contact of humerus with acromion and coracoid) during 5 ADLs (hand to opposite shoulder, hand to back of head, hand to mouth, drink from mug and place object to head height).Introduction
Methods
Reverse shoulder prosthesis has been developed to treat the clinical and pathological condition noted as cuff tear arthropathy (CTA). The current models of reverse shoulder arthroplasty (RSA) expose the procedure to the risk of scapular notching, possibly leading to loosening of the glenoid. The purpose of this study was to report updated results at a minimum follow-up of four years of 25 patients underwent reverse shoulder arthroplasty between 2006 and 2010 with an eccentric 36-mm glenoid component (SMR Lima).Introduction
Aim
Reverse shoulder arthroplasty (RSA) is a reasonable treatment modality in patients with Cuff Tear Arthropaty and massive irreparable cuff tears. RSA has been shown to increase patient function and decrease pain. The aim of this study is to evaluate the clinical and radiographic results of a 44 polyethylene glenosphere. Since 2008 we treated 88 patients with cuff tear arthropaty and irreparable massive cuff tear, using an RSA. We selected 80 patients with minimum FU of 24 months in which we used an implant with polyethylene glenosphere and metal humeral insert. Size of the glenosphere used was 44. All patients were assessed with the Constant score and with VAS. The shoulder ROM was measured preoperatively and postoperatively.Introduction:
Methods:
The aim of this retrospective study is to evaluate clinically and radiographically the effectiveness of implanting an eccentric glenosphere and if a correct glenosphere positioning would avoid the occurrence of notching. since 2006 40 patients with shoulder eccentric osteoarthritis were treated with reverse shoulder arthroplasty with a 36 mm eccentric glenosphere. We have selected 25 patients, with a minimum follow up of 24 months. The patients were clinically evaluated with the Constant score and SST and with X-ray, MRI and/or CT before and after surgery. At the follow up we evaluated the presence or absence of notch, and we measured the PSNA (prosthesis-scapular neck angle), the DBSNG (distance between the scapular neck angle and glenosphere), the PGRD distance (peg glenoid distance). Stastistical analysis was performed with a paired t test.INTRODUCTION
METHODS
Reverse shoulder prosthesis may lead to scapular notching, caused by attrition of the upper humeral component with scapular neck. We compared the clinical and radiographic results obtained with a SMR prosthesis, which allows a concentric or an eccentric glenosphere to be applied. 67 patients, mean age 73 years, were treated with reverse prosthesis using concentric and eccentric glenosphere. In patients with concentric glenosphere, the glenosphere extended about 4 mm below the glenoid. The eccentric glenosphere protected the upper glenoid neck by its inferior prolongment. Patients were followed for a mean of 33 months. At final F-U the Constant Score (C.S.) and the score with the Simple Shoulder test (S.S.T.) were calculated. Radiographs were obtained to evaluate the presence of scapular notching, psna (prosthesis-scapular neck angle), pgrd (peg- glenoid rim distance) and DBSNG (distance between scapular neck and glenosfere). Included in this study were patients, as much homogeneous as possible by age and pathology, 25 with concentric (Group I) and 30 with eccentric (Group II) glenosphere, who had a minimum F-U of 24 months. Statistical analysis was performed with a paired test.Purpose
Patients and methods
the aim of the study is to evaluate the clinical results of the shoulder prosthesis revision procedure to reverse implant without removing the humeral stem using a modular system (Lima LTD) and determine if this procedure is beneficial for the patients. e selected only the patients where a revision to reverse (RSA) of hemiarthroplasty (Hemi) originally implanted for fracture (Group I) and revision to reverse (RSA) of anatomical total prosthesis (TSA) were performed. From 2004 to 2009 26 cases responding to these parameters were identified: 18 cases in Group I (failed hemiarthroplasty for tuberosities resorptions or rotator cuff failure) and 8 in Group II (failed TSA for rotator cuff omplication). The mean follow-up was 32 months (min 18–max 76) and the mean age was 72 (min 65–max 80) Clinical assessment was performed with preoperative and postoperative Constant score rating scale (CS) and range of motion evaluation (ROM) Radiological assessment was performer by AP and Axial X-ray views. Operative time was calculated.Introduction
Methods
Total shoulder replacement is a successful procedure for degenerative or some inflammatory diseases of the shoulder. However, fixation of the glenoid seems to be the main weakness with a high rate of loosening. The results using all-polyethylene components have been better than those using metal-backed components. We describe our experience with 35 consecutive total shoulder replacements using a new metal-backed glenoid component with a mean follow-up of 75.4 months (48 to 154). Our implant differs from others because of its mechanism of fixation. It has a convex metal-backed bone interface and the main stabilising factor is a large hollow central peg. The patients were evaulated with standard radiographs and with the Constant Score, the Simple Shoulder Test and a visual analogue scale. All the scores improved and there was no loosening, no polyethylene-glenoid disassembly and no other implant-related complications. We conclude that a metal-backed glenoid component is a good option in total shoulder replacement with no worse results than of those using a cemented all-polyethylene prosthesis.
